1. Field of the Invention
The present invention relates to a method of repairing a chamber type coke oven. Specifically, the present invention relates to a method of repairing damaged walls of combustion chambers near oven openings of a coke oven with high efficiency. It further relates to a method of relaying bricks to build up coke oven walls, to a method of heat-insulating a part of a coke oven during repair of a brick wall therein, and to an apparatus for taking bricks into a coke oven for repair. More particularly, the present invention relates to a coke oven repairing method which is applicable even to a coke oven having combustion chambers with a complicated brick structure, such as a Carl Still coke oven.
2. Description of the Related Art
Generally, as shown in FIG. 1, a coke oven includes a regenerator 9 in its lower portion, and a plurality of coking chambers 2 and combustion chambers 4 arranged alternately side by side in its upper portion, thereby constituting an oven battery. Coal is charged into the coking chambers 2 from a charging car 51 traveling over the coke oven, and is carbonized under heat applied from the combustion chambers 4 on both sides. After opening a door 8 of each coking chamber 2, the carbonized coal, i.e., coke, is pushed out from the coking chamber 2 into a quenching car 53 via a guide car 54 by a pushing machine 52, followed by being transported to a red coke quenching facility (not shown) in the quenching car 53.
The regenerator 9 and the combustion chambers 4 are constructed using bricks. Inside the regenerator 9 and the combustion chambers 4, there are formed passages through which flow the fuel gas, air and combustion exhaust gas generated when the fuel gas mixes with air and burning. In particular, the combustion chambers 4 are each structured by laying bricks in a combined manner to form those passages. Outer wall surfaces of the combustion chamber 4 serve also as brick wall surfaces of the adjacent coking chambers 2. Thus, each coking chamber 2 is a space surrounded by the outer wall surfaces of the two adjacent combustion chambers 4, the door 8 at the side near the pushing machine 52, and a door 10 at the side near the guide car 54.
For carbonizing coal in the coking chambers 2 into homogeneous coke, the temperature in the coking chambers 2 needs to be kept as uniform as possible. To that end, various types of structures have been proposed relating to the passages for the fuel gas, air and the combustion exhaust gas which is formed in the regenerators 9 and the combustion chambers 4.
FIG. 2 is a perspective sectional view of Carl Still type coke ovens, as an example having two-divided combustion chambers and having horizontal flues at the top of each row of combustion chambers. In a two-divided type coke oven, the combustion chamber 4 and the regenerator 9 are each divided into two sides: the pushing-machine located side (machine side: hereinafter abbreviated to M/S) 17 and the guide-car located side (coke side: hereinafter abbreviated to C/S) 16, both of the sides being coupled via a horizontal flue 14 at the top of the combustion chamber 4. The direction in which the M/S and C/S are interconnected is referred to as the longitudinal direction of the oven; it is indicated by arrow 18 in FIG. 2. The direction along which the combustion chambers and the coking chamber are alternately arranged side by side is referred to as the transverse direction of the oven; it is indicated by arrow 19 in FIG. 2.
Still referring to FIG. 2, fuel gas 61 and air 62 for combustion are both supplied from below the regenerator 9 of the C/S flow through the passages in the regenerator 9 for preheating, and then flow upwardly through the combustion chamber 4. Within the combustion chamber 4, the fuel gas passages and the air passages have openings formed in multiple stages for communication with vertical flues 11. The openings in the fuel gas passages are referred to as gas ports, and the openings in the air passages are referred to as air ports. The fuel gas 61 and the air 62 are mixed with each other in the vertical flues 11, whereupon the fuel gas burns. The fuel gas passages and the air passages in the combustion chamber are each called a multistage burner duct 12. Flows of the combustion exhaust gas generated in the vertical flues 11 join together in the horizontal flue 14, advance in the longitudinal direction of the oven, and reach the M/S of the combustion chamber. Then, the combustion exhaust gas flows downward from the upper horizontal flue 14 into vertical flues 11 of the M/S, goes into multistage burner ducts 12 through gas ports and air ports in a reversed direction as compared to that in the C/S, and passes the regenerator 9, followed by being exhausted from a smokestack 20. After continuing the above combustion process for 20 to 30 minutes, the fuel gas 61 and the air 62 are supplied from the M/S oppositely. The combustion exhaust gas flows from the M/S to the C/S, and is then exhausted. As a result of repeating the above two combustion process alternately, the temperatures in both the C/S and M/S of the combustion chamber are kept uniform.
In this way, the coke oven of FIG. 2 is operated so that the temperature is kept as uniform as possible throughout the oven. At the time of discharging the produced coke to the outside of the oven, however, the doors at both ends are opened and the coke is pushed out by the pushing machine as described above. Therefore, open air flows into the oven, and the oven walls near the doors are subjected to abrupt rising and falling of temperature. It is also inevitable that the wall surfaces of the coking chambers are abraded by the coke being pushed out. Accordingly, the use of the coke oven for a long period of time often gives rise to significant damage of the oven walls, particularly near the doors. In the case of serious damage, the oven is repaired by hot-relaying of bricks to form the oven walls.
Heretofore, the wall of a coking chamber has been repaired as follows.
First, two adjacent coking chambers are emptied. Then, combustion is ceased in one combustion chamber formed in an oven wall to be repaired and in two combustion chambers adjacent to the former. Simultaneously, a heat-insulating material is installed so as to surround an area covering from the boundary between a rebuilt (repaired) portion and a not-repaired portion of the one combustion chamber to the oven openings between the two combustion chambers. The reason for surrounding the rebuilt portion with the heat-insulating material is to prevent temperature drop of bricks in the not-repaired portion of the one combustion chamber and bricks in the two adjacent combustion chambers. Another reason is to accelerate cooling of bricks in the rebuilt portion at the same time. The temperature in the working space is thus lowered to such a level as to allow the start of brick relaying work.
After supporting ceiling bricks of the rebuilt portion by hanging hardware to prevent those bricks from dropping, the brick wall in the rebuilt portion is dismantled and oven fastening hardware is removed. The all serving as a partition between the two adjacent coking chambers is partly dismantled. Subsequently, in the positions left open after dismantling, new bricks are manually laid one by one to restore the wall, and the oven fastening hardware is installed.
In laying bricks one by one, the thickness of joints between bricks laid in the repaired portion and the positions of bricks fitted to each other are adjusted. For adjustment, the dimensions of the space left open after dismantling the brick wall to be rebuilt are measured, and the dimensions of a rebuilt brick wall in a condition after the oven temperature has been completely raised are calculated, taking into account the three-dimensional position of the not-repaired portion of the brick wall of the combustion chamber, and the thermal expansion of the bricks used. As a result, a smooth and continuous wall surface is formed between the not-repaired portion and the repaired portion of the brick wall of the combustion chamber. In the work for pushing out coke after the start of operation of a coke oven, therefore, the frictional resistance between the coke and the wall surface can be reduced.
With the above repairing method, however, because bricks are laid and bonded one by one in a narrow oven space, the repairing work takes a long time. Also, an extended shutdown time of the facility brings about a remarkable reduction of production. Further, the oven temperature in the repaired portion is lowered, but it cannot be fully lowered down to the temperature of open air. In other words, the work of rebuilding the oven brick wall imposes a great load upon the workers.
To solve the above-mentioned problem, Japanese Unexamined Patent Publication No. 4-213388 discloses a method of repairing a damaged portion of a heating wall of a coke oven by using large-sized module bricks each molded into a one-piece structure. The module brick is molded so as to provide flues and coking chamber wall surfaces in the integral form which constitute a combustion chamber of the coke oven, and is manufactured prior to the relaying work. The disclosed method employs, as a unit brick, the module brick having a larger size than the conventional unit brick. Accordingly, the disclosed method can shorten the time required for the repairing work in the coke oven, and reduce the working load. Further, the oven shutdown time during the repairing work can also be shortened. It is thus possible to suppress a reduction rate of coke production, and simultaneously to cut the working time.
However, the module brick is large in both size and weight. A hoist or the like is necessary to lay such a large-sized brick to a predetermined position in the coke oven But it is not easy to fixedly install a hoist beam because the ceilings, walls, etc. of combustion chambers and coking chambers of the coke oven are constructed of bricks. Also, even if a hoist beam could be installed to extend from a position above a brick-laid portion of the combustion chamber to the outside of the oven, the hoist beam extended to the outside of the oven may interfere with any other traveling car or machine traveling outside the oven.
Another problem with the use of module bricks is a difficulty in precisely laying the module bricks to rebuild the brick wall. When building a coke oven in a conventional way, manually laid bricks each usually have a height of 130 cm and a weight of not more than 10 kg, at maximum a height of 250 cm and a weight of 25 kg. In the case of using such a brick, the vertical load imposed on mortar (bond) applied as a horizontal joint is relatively small, ie., in the range of 0.025-0.06 kg/cm2. Therefore, even when mortar prepared to have a relatively small consistency (according to JIS (Japanese Industrial Standards R2506: consistency of mortar) is used, the bricks can be laid one above another strictly as designed with a joint thickness of 3-5 mm. In other words, the bricks can be precisely stacked up in a short time after applying the mortar. In the case of laying bricks having a larger height and a greater weight, however, the vertical load imposed on the applied joint mortar is increased. Consequently, when mortar suitable for short-time work is employed, the applied joint mortar may be overly depressed and shrunk before developing its own strength, thus causing difficulty in precisely laying the bricks one above another.
Further, in a coke oven having combustion chambers with a complicated brick built-up structure, such as a Carl Still coke oven, it is very difficult to form module bricks themselves.
Module bricks for use in a Koppers coke oven (disclosed in, e.g., the above-cited Japanese Unexamined Patent Publication No. 4-213388), for example, can be manufactured with ease. In the Koppers coke oven, a flue formed in the combustion chamber extends straight from the lower end of the combustion chamber to the upper end thereof, and then returns to the lower end after turning around at the upper end. A large number of flues having such a configuration are arranged in parallel to form the combustion chamber. Thus, the module bricks for use in the Koppers type coke oven each have such a simple shape that vertical bores are formed through a large-sized brick. It is therefore not so difficult to mold those module bricks.
In a Carl Still coke oven, however, the combustion chamber has three types of passages, i.e., gas passages, air passages and flues, all of which extend from the lower end of the combustion chamber to the upper end thereof. Further, at several points within a brick wall of the combustion chamber in the vertical direction, oblique openings are formed to extend from the gas passage and the air passage to the corresponding flue. When trying to form the combustion chamber in the Carl Still coke oven using module bricks, therefore, not only the vertical passage bores but also the oblique openings must be provided in the wall brick. Stated otherwise, the problem arises that a large-sized module brick to be manufactured, has a complicated internal structure and that dimensional accuracy is reduced during firing of the module brick.
Module bricks are molded by pouring a refractory material in molds and firing the material. Therefore, a large number of module bricks are manufactured beforehand to have a certain configuration and dimensions as per designed, and are used in repairing a coke oven. In general, the brick wall surfaces of the coke oven are deformed due to the use for many years, and particularly vertical surfaces are often inclined. In view of such a deformation, surfaces of a rebuilt brick wall are adjusted at joints when bricks are laid one above another. In the case of laying module bricks one above another, the number of joints in the vertical direction is smaller than the case of stacking ordinary unit bricks one by one. For that reason, when the module bricks are laid one above another, an amount of adjustment to be made at each joint is increased, discontinuous steps are inevitably left at the joints, and a smooth wall surface cannot be formed as a whole. If an uneven wall surface is left unchanged, the frictional resistance between the wall surface and coke after the start of operation of the coke oven would be increased and the period until next repair would be shortened. To avoid such problems, discontinuous steps in the wall surface must be cut with a cutter or a sander to smooth the wall surface after build-up of the module bricks. This work however prolongs the total time required for the bricklaying work at high temperatures, and offsets the advantage from employing the module bricks.
Further, in a two-divided type coke oven having a horizontal flue at the top of a combustion chamber, hot air cannot be perfectly blocked off just by covering wall surfaces of both adjacent coking chambers with heat-insulating materials. More specifically, because the top horizontal flue is extended throughout the combustion chamber in the longitudinal direction of the oven, hot air is blown off from vertical flues in the unrepaired portion of a brick wall through the top horizontal flue. In addition, the rebuilt portion of the brick wall is also communicated with an underlying regenerator through multistage burner ducts and gas ports at the bottom ends of the vertical flues. Accordingly, as dismantling of bricks progresses, there occurs a blowoff of hot air through gas ports and air ports of the multistage burner ducts and the gas ports at the bottom ends of the vertical flues. No method of effectively preventing such a blowoff of hot air for positive heat insulation has yet been proposed.
Moreover, to prevent brick scraps generated during dismantling of the bricks from scattering through openings in communication with the regenerator, those openings must be covered to keep the brick scrap positively from dropping into the regenerator through the openings.
An object of the present invention is to provide a method of repairing a coke oven with which coke oven walls deformed in various ways due to use for many years, can be precisely repaired with high efficiency. More particularly, the present invention provides a coke oven repair method which can shorten the working time under a high temperature environment, can reduce the load of brick relaying work, and can precisely repair damaged brick walls even when repairing a complicated coke oven. The present invention also provides a concrete heat-insulating method capable of improving the working environment. It further provides a method of preventing brick scraps from dropping down to undesired locations. It also relates to an apparatus for taking bricks into a coke oven.
To achieve the above objects, the present invention provides a method of repairing a coke oven and an apparatus for talking bricks into a coke oven as follows.
More specifically, in hot-relaying/-repairing a part of a combustion chamber brick wall of a coke oven, the method comprises the steps of heat-insulating a repair space in the oven, dividing a brick wall in a portion to be repaired into a plurality of layers stacked one above another, dismantling and removing the brick wall in the repaired portion, and carrying refractory assemblies into the oven one by one, each of the refractory assemblies being manufactured outside the oven by combining a plurality of bricks together to assume a shape corresponding to each of the stacked layers in one-to-one relation, thereby building the brick wall in the repaired portion with the refractory assemblies. Also, in the method of repairing a coke oven, the refractory assemblies are carried into the oven by using an apparatus for taking bricks into the oven, the apparatus comprising an in-oven beam fixed to ceiling hanging hardware and installed through eyeholes formed in the combustion chamber ceiling of the oven, an ex-oven beam extending from the in-oven beam to the outside of the oven, a suspension device for lifting up and down a suspended load and moving along the in-oven beam and the ex-oven beam, and a brick gripping device suspended from the suspension device. Further, in the repair method, the coke oven is of the 2-divided type having a horizontal flue at the top of a combustion chamber, and the repair space in the oven is heat insulated, for example, by closing upper end openings of two or more vertical flues with a heat-insulating material, the vertical flues being located in an unrepaired portion adjacent to a repaired portion, and by blocking off the horizontal flue over its full cross-section.